I use the College Clock from More Awesome Than You, which can be found here:
http://www.moreawesomethanyou.com/ffs/uni/hacks/Two nice things about this: the clock is cheap (only 5 simoleons) and you can keep your game on pause. Just click on the clock, highlight "My LTW is Lame", and keep clicking the clock and checking your LTW bar until it shows one that you like. Then save the game, and either delete the clock or just keep it around for future use.
(Note: I have all EPs installed, including Seasons, and have never had a problem with compatibility issues)
If there's an easier way to do it I'd be interested in hearing it, but this is the best I've found.
RA